OpenWrite Method (String)

WebClient.OpenWrite Method (String)

Opens a stream for writing data to the specified resource.

Namespace: System.Net
Assembly: System (in system.dll)

Public Function OpenWrite ( _
	address As String _
) As Stream
Dim instance As WebClient
Dim address As String
Dim returnValue As Stream

returnValue = instance.OpenWrite(address)
public Stream OpenWrite (
	String address
public function OpenWrite (
	address : String
) : Stream
Not applicable.



The URI of the resource to receive the data.

Return Value

A Stream used to write data to the resource.

Exception typeCondition


The URI formed by combining BaseAddress, and address is invalid.


An error occurred while opening the stream.

The OpenWrite method returns a writable stream that is used to send data to a resource. This method blocks while opening the stream. To continue executing while waiting for the stream, use one of the OpenWriteAsync methods.

If the BaseAddress property is not an empty string ("") and address does not contain an absolute URI, address must be a relative URI that is combined with BaseAddress to form the absolute URI of the requested data. If the QueryString property is not an empty string, it is appended to address.

This method uses the STOR command to upload an FTP resource. For an HTTP resource, the POST method is used.


This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing.

The following code example reads data from the command line and uses OpenWrite to obtain a stream for writing the data. Note that the Stream returned by OpenWrite is closed after the data is sent.

Dim uriString As String
Console.Write(ControlChars.Cr + "Please enter the URI to post data to : ")
uriString = Console.ReadLine()
Console.WriteLine(ControlChars.Cr + "Please enter the data to be posted to the URI {0}:", uriString)

Dim postData As String = Console.ReadLine()

' Apply ASCII Encoding to obtain an array of bytes .
Dim postArray As Byte() = Encoding.ASCII.GetBytes(postData)

' Create a new WebClient instance.
Dim myWebClient As New WebClient()

Console.WriteLine("Uploading to {0} ...", uriString)

' OpenWrite implicitly sets HTTP POST as the request method.
Dim postStream As Stream = myWebClient.OpenWrite(uriString)
postStream.Write(postArray, 0, postArray.Length)

' Close the stream and release resources.

Console.WriteLine(ControlChars.Cr + "Successfully posted the data.")

String uriString;
Console.Write("\nPlease enter the URI to post data to : ");
uriString = Console.ReadLine();
Console.WriteLine("\nPlease enter the data to be posted to the"
    + " URI {0}:", uriString);
String postData = Console.ReadLine();
// Apply Ascii Encoding to obtain an array of bytes. 
ubyte postArray[] = Encoding.get_ASCII().GetBytes(postData);
// Create a new WebClient instance.
WebClient myWebClient = new WebClient();
// postStream implicitly sets HTTP POST as the request method.
Console.WriteLine("Uploading to {0} ...", uriString);
Stream postStream = myWebClient.OpenWrite(uriString);

postStream.Write(postArray, 0, postArray.get_Length());
// Close the stream and release resources.

Console.WriteLine("\nSuccessfully posted the data.");

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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